The present invention relates to a hybrid refrigerant compressor mainly used for motor vehicle air-conditioning systems.
The present invention pertains to a hybrid refrigerant compressor having a driveshaft driven by a plurality of drive sources. The drive sources include a belt driven pulley powered by the vehicle""s prime mover engine and an electric motor that can drive the air-conditioning system compressor when the vehicle engine is not operating.
Generally, a vehicle air-conditioning system includes a refrigeration circuit which includes a compressor and an external circuit connected to the compressor. When the compressor is driven by the engine, refrigerant circulates in the refrigeration circuit and cools the passenger compartment. Typically, the compressor is connected to a single drive source; namely, the vehicle""s engine, driving a belt wrapped on a pulley with an electromagnetic clutch. When the cooling capacity of the refrigeration circuit becomes excessive as the thermal load on the refrigerator circuit decreases, the electromagnetic clutch is de-energized and the operation of the compressor is temporarily stopped. When the engine has stopped, the compressor is not operated and the cooling function is stopped whether the electromagnetic clutch is turned on or off. When the engine is stopped, the compressor can be driven by the motor to cool the passenger compartment. This is a particular problem in so-called hybrid vehicles, in which the prime mover engine may generate electricity to drive electric motors with energy from storage batteries. These vehicles may have operating modes in which cooling is required when the engine is not operated.
Current hybrid compressors use a common shaft through the compressor either driven from the front by the belt driven pulley or the rear by an electric motor. Upon engagement, the electromechanical clutch attached to the front of the compressor must overcome the momentum of not only the compressor but also the momentum of the rotor of the electric motor. This puts high loads on the compressor drive shaft and the clutch, and causes an engine rpm drop. The compressor controls must also manage the transient electricity produced by the drive motor while the compressor is being driven by the belt driven pulley.
In this invention a bearing clutch assembly interacts with the rotor of the electric motor that allows the motor to drive the driveshaft or let it freewheel. By doing this, the rotor is supported on the bearing assembly during the belt driven pulley operation and the momentum of the rotor is not seen by the clutch being driven from the engine. When the compressor is powered from the electric motor, the bearing clutch is engaged, enabling the compressor to be turned via the electric motor.
Other aspects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.